The invention relates, in particular, to taps for gas cylinders or bottles which can be refilled by the user himself at a gas-distribution point. To comply with safety regulations, when filling a bottle of this type correctly it is necessary to avoid filling the bottle completely so as to leave a gaseous zone, above the liquefied gas, which can act as a buffer in the event that the bottle is exposed to a source of heat and, optionally, be released via a safety valve. Unfortunately, these regulations are not always complied with, either because of a lack of means for monitoring during the filling or because of negligence on the part of the user, so that the safety valve is the only safety feature.
U.S. Pat. No. 5,282,496 proposes a tap which allows the gas to be drawn off and the bottle to be filled via the tap and a level valve which, during filling, automatically halts the penetration of the gas when the gas in the bottle reaches a preset level.
As the gas is drawn off via the level valve, the drawing-off rate is not very high, which means that this tap is unsuitable for industrial applications in which large quantities of gas have to be tapped off.